Concentrations of airborne Bacterial 16S rDNA gene copies determined by qPCR analyses for different fuel/engine type and tourist buses. The number above each of the boxes refers to the number of samples taken in each kind of fuel bus
Public bus system worldwide transports daily more than 34 million people; therefore, air quality inside buses is an important urban air pollution issue. Airborne microbiological composition and abundance was examined inside five different fuel type buses (diesel (EURO IV and EURO V), hybrid diesel (HD), compressed natural gas (CNG), hybrid natural...
The measurement of airborne endotoxins is often necessary because of the inhalation of these lipopolysaccharides from most Gram-negative bacteria is known to provoke harmful effects on worker’s health including acute respiratory symptoms. Sampling on filters is one of the most widely used methods for measuring endotoxins in the air, and the present article confirms that there is a wide variety of filters used for the measurement. This article provides an expert opinion based on a mini review on the influence of the nature of the filter used on the measurement results. First, the analysis of published studies shows that the measurement of endotoxins, either at the workplace or in laboratory conditions, is carried out with different measurement protocols from one study to another, at least with regard to the filter used. Secondly, this is questioning since the equivalence of protocols in terms of measurement performance has not been fully investigated. In particular, the review of studies that have investigated the effect of the filter on the measurement of airborne endotoxins is quite contradictory, and no recent published study has provided any tangible evidence. This leads to the conclusion that the current recommendations regarding the type of filters to be used for endotoxin measurements are based on insufficient data. Thus, additional experimental studies are required. Thirdly, a detailed and argued survey of the mechanisms involved in the measurement has been carried in order to facilitate the construction of further studies. This allowed identifying the factors, including either physical or chemical properties of the filter, to be taken into account in studies on the effect of the filter on the measurement of endotoxins in the air and specifying the issues that have not yet been investigated. Finally, the results of these studies should allow a more objective orientation towards a given type of filter and could complement the recommendations of the EN14031 standard.